Abstract
Purpose: :
The purpose of this study was to describe the growth patterns of the human orbit by measurement of volume, height, width and depth. The locations of the anterior ethmoidal foramen, optic nerve and the presence of an infra-orbital notch or foramen are important surgical landmarks which may vary more than indicated in previously published reports.
Methods: :
Native North American Human skulls (n=70) from the Peabody Museum at Harvard were measured for width from the dacrion to lateral wall, perpendicular height and depth from the dacrion to the medial wall of the optic nerve. These linear measurements were made using three repeated readings with calipers and paper rulers. Volumetric assessments of the orbits were performed using 1mm glass beads and graduated cylinders. Data were analyzed using linear and quadratic function regression analyses and as age group years <3, 3-7, >7-11, >11-16, >16 (M=31 years; SD=9) at a significance threshold of p<.05.
Results: :
There was high variability in the position of the ethmoidal foramen and the optic nerve. The horizontal width appeared more closely correlated with depth than was age. Horizontal width was more strongly correlated with the depths to the anterior ethmoidal foramen (R2=.54, p<.000001) than Vertical height (R2=.14, p<.001). Depths to the medial wall of the optic nerve were weakly related to Horizontal width (R2=.07, p<.02) and Vertical height (R2<.01, p=.48). Linear and Volume data showed growth beyond 16 years, with approximately 15% increase in volume with each incremental age banding.
Conclusions: :
Depth for ethmoidal foramen and artery vary greatly between individuals, regardless of published depths, with Horizontal width and age as the strongest predictors of position. Optic nerve positions were highly variable and much less predictable from external anatomy measurements or age. In contrast to previously published reports, Orbital volume appears to increase beyond puberty. Surgeons should be especially cautious in relying on published dogma for depth to the optic nerve or the ethmoidal artery. Surgeons planning implant surgery should take into account that eye growth may continue after puberty.
Keywords: anatomy • orbit • development